Electromagnetic drive systems are often used in electrical engineering to apply force on movable mechanical components. Such systems use for example pull magnets or other electromagnetically operative component assemblies. These drive systems are used inter alia in contactors, circuit breakers, relays, solenoid valves, etc. in various forms.
In the actuating of such drive systems, the magnetic system is usually directly energized by the control voltage source; an acceleration of mechanical components thereby occurs such as e.g. armature or lever systems. That causes, for example, the closing of switch contacts. However, the force curve and closing speed in this case depend on the amount of voltage applied.
Yet it is also known that the energy supply of drive systems is often controlled by electronic assemblies (ballasts) such that the displacement/time characteristic of the force curve optimally corresponds to the requirements of the mechanical system during actuation
Already known from DE 20 2011 051 972 U1 is a circuit arrangement for actuating a switching device which exhibits a first switch position and a second switch position and can be switched between the first switch position and the second switch position and comprises at least one electromagnetic actuating device for generating a actuating force for switching the switching device between the first switch position and the second switch position and a trigger circuit for actuating the electromagnetic actuating device.
The actuation of the aforementioned drive systems by directly loading the magnetic systems with the available control voltage has the disadvantage of the supplied control current and thus the magnetic force usually not being adapted to the existing force/displacement characteristic of the powered mechanical system.
The known electronic ballasts for operating magnetic drive systems directly clock the magnetic systems via one or more electronic switches. Thereby disadvantageous is that while the available control voltage can be reduced, it cannot be increased.
Yet it is advantageous in a number of applications of said drive systems to also be able to increase the actuation control voltage if needed. Otherwise in such applications—for example in undervoltage situations—safe actuation is not possible.
Furthermore, these ballasts preferably serve in the actuating of switching devices in the form of in contactors in which the power requirement is initially high but which then drops over time.
The direct clocking of the electrical drive system additionally results in an interference voltage spectrum which can negatively affect other electronic systems. The pulse gradient also causes an increased loading of the coil structure of the magnetic systems which are mostly designed for DC or low-frequency AC operation. The clocked mode of operation can thus cause damage to the winding of the magnetic system.
It is therefore the task of the present invention to further advantageously develop a circuit arrangement and a method for operating a circuit arrangement, in particular to the effect of ensuring reliable and less mechanically aggressive operation without substantial emitted interference across the entire input voltage and temperature range and enabling the actuating of such drive systems having a greatly increasing power requirement over time during actuation as well as a mechanically locked stable end position.
The invention solves this task by a circuit arrangement having the features of claim 1. According thereto, a circuit arrangement is provided for the actuating of an electro-magnetic drive system for electromechanical devices, in particular comprising a mechanically locked end position, at least one control voltage source, at least one regulating and control circuit, at least one drive system, at least one transformer, at least one rectifier bridge, at least one smoothing capacitor, at least one main switching transistor, by means of which the drive system can be controlled in a characteristic pulse tracking system and wherein the main switching transistor is connected in series to a primary branch of the transformer, wherein the transformer is connected to the supply voltage and the secondary winding of the transformer supplies the rectifier bridge, the output DC voltage of which is smoothed by the smoothing capacitor and added to the voltage of the control voltage source so as to result in a DC voltage feed having a chronological supply progression.
The invention is based on the basic concept of a clocked transformational converter stage providing the electrical supply characteristic required for the specific operation of the electromagnetic drive system throughout the entire input voltage and temperature range without pulsed loading of the drive system coils by way of a control and regulating circuit. The disadvantages of the known control systems identified in the prior art are avoided and a circuit arrangement is provided which operates the magnetic system of said drive systems, in particular those with DC solenoid coils, such that reliable and less mechanically aggressive operation without substantial emitted interference is ensured throughout the entire input voltage and temperature range and also allows the actuating of such drive systems having a greatly increasing power requirement over time during actuation as well as a mechanically locked stable end position.
The operation of switching devices having electromagnetic drive systems, for example battery circuit breakers having drive system pull magnets and a mechanically locked end position, contactor and relay coils as well as solenoid valves with electromagnetic valve control, gives rise to limited operating voltage ranges and increased wear of the mechanically moved components due to the internal structure. Clocked voltage operation gives rise to emitted interference which can affect electronic circuits.
To avoid these disadvantages, a circuit arrangement is now inventively provided which supplies a regulated DC voltage having a beneficial supply progression for the drive system by means of a switching stage and transformer arrangement with a downstream rectifier and also enables the actuating voltage to be increased over the existing and possibly highly tolerance-dependent control voltage when needed. This thereby ensures their safe activation, as in the example case of a battery circuit breaker having drive system pull magnets and a battery-backed power supply system subject to a wide input voltage range. The circuit arrangement moreover enables a delicate and thus life-extending mode of operation for the mechanically moved components. Feeding DC voltage to the drive system largely prevents emitted interference, particularly in the case of longer wirings between the described circuit arrangement and the drive system.
An auxiliary diode connected to the transformer/main switching transistor node on the anode side and to the rectifier bridge cathodes node on the cathode side can be provided.
The rectifier bridge can be formed by a plurality of diodes. These diodes can, for example, be fast diodes for output rectification.
It can furthermore be provided for a second transistor to be furnished and for the switching arrangement to be switchable such that a hold circuit can be activated in the power circuit by means of a second transistor using the return magnetization energy of the transformer for the activation time via the processing of a gate voltage, whereby the second transistor is activated and is disabled after the activation time by the switching off of the main switching transistor and the ceasing of the return magnetization energy.
It is moreover possible for the control and regulating circuit to comprise a PWM circuit (PWM=pulse width modulation) with activation time limitation and for a pulse pattern corresponding to the specifics of the drive system able to be assigned to the respective application by an appropriate selection to be stored via the PWM circuit.
It can furthermore be provided for the circuit arrangement to comprise a microcontroller circuit and for the microcontroller circuit to be used for the coordinated control and pulse processing.
Additionally possible is for a thermal fuse, in particular a reversible thermal fuse, and a series resistor for the control current supply to be arranged such that in the event of failure in the main current path, the combination of thermal fuse and series resistor can be arranged and switched such that the main current path is interruptible via the thermal coupling of the thermal fuse and series resistor.
It can furthermore be provided for the circuit arrangement to further comprise a safety circuit having an optocoupler and a Z-diode which can be switched such that in the event the output load is interrupted, inadmissibly high output voltage can thereby be prevented by the safety circuit responding in the event of failure such that the optocoupler is activated by the excessive output voltage via the Z-diode and the output of the optocoupler thereby acts on the control and regulating circuit, with the activation period thus being reduced for the power transistor such that the output voltage remains restricted to a permissible level.
The present invention further relates to a method for operating a circuit arrangement.
In one method of operating a circuit arrangement for the actuating of an electromagnetic drive system for electromechanical devices, in particular comprising a mechanically locked end position, at least one control voltage source, at least one regulating and control circuit, at least one drive system, at least one transformer, at least one rectifier bridge, at least one smoothing capacitor, at least one main switching transistor, by means of which the drive system can be controlled in a characteristic pulse tracking system in at least one operating state and wherein the main switching transistor is connected in series to a primary branch of the transformer, the process is thereby for the transformer to be connected to the supply voltage and the secondary winding of the transformer to supply the rectifier bridge, the output DC voltage of which is smoothed by the smoothing capacitor and added to the voltage of the control voltage source so as to result in a DC voltage feed having a chronological supply progression.
It can furthermore be provided for a second transistor to be furnished and for the switching arrangement to be switched during operation such that a hold circuit can be activated in the power circuit by means of a second transistor using the return magnetization energy of the transformer for the activation time via the processing of a gate voltage, whereby a second transistor is activated and is disabled after the activation time by the switching off of the main switching transistor and the ceasing of the return magnetization energy.
It is moreover possible for the regulating and control circuit to comprise a PWM circuit with activation time limitation and for a pulse pattern corresponding to the specifics of the drive system able to be assigned to the respective application by an appropriate selection to be stored via the PWM circuit.
Additionally possible is for a thermal fuse, in particular a reversible thermal fuse, and a series resistor for the control current supply to be arranged such that in the event of failure in the main current path, the thermal fuse and series resistor combination can be switched such that the main current path is interrupted via the thermal coupling of the thermal fuse and series resistor.
It can additionally be provided for the circuit arrangement to further comprise a safety circuit having an optocoupler and a Z-diode which can be switched in the event of failure such that if the output load is interrupted, inadmissibly high output voltage can thereby be prevented by the safety circuit responding in the event of failure such that the optocoupler is activated by the excessive output voltage via the Z-diode and the output of the optocoupler thereby acts on the control and regulating circuit, with the activation period thus being reduced for the power transistor such that the output voltage remains restricted to a permissible level.